The present invention generally relates to a system for line-conducted digital data transmission and, in particular, relates to one such system including a transfer point accessible to the subscriber whereat a digital transmission path is immediately and directly available the subscriber.
In general, arrangements for lead-conducted digital data telecommunication between a switching exchange of a telecommunication network and a subscriber connected to this network are known from the German magazine "ntz" vol. 45 (1992), issue 11, pages 902 and 903.
Digital telecommunication technology with its attendant advantages over analog technology, for example, by the provision of a larger range and a high transfer rate, is becoming more widely used in the telecommunication field. In general, there are many digital telecommunication technology services that may be used by subscribers of a modern telecommunication network. Typically these include such devices as telephone, telefax, telex, teletex, IDN and ISDN basis connections and primary multiplex connections. As a result, the subscriber connection portion of the network, generally referred to as the subscriber loop, is of special importance.
Such a subscriber loop with the name "Opal" for a pilot project of the DBP Telecom is described in the German magazine "ntz" VOL. 45 (1992), issue 11, pages 902 and 903. Therein, a selected number of subscribers are connected to the switching exchange via glass fibers or light waveguides. Therein, a light waveguide passes from the switching exchange to a remote optical line concentrator, from which it passes to the buildings and to a service access point. In this passive subscriber loop the light signal power is divided according to the number of subscribers connected to the subscriber loop. Hence, there is a limit to the number of subscribers that can be connected to the loop. In addition, such a system is adapted for use with lasers having wavelengths of, for example, between 1330 nm or 1550 nm. Additionally, the particular devices of the subscribers, such as telephone and data terminals, are connected by analog means to so-called line terminal equipment, wherein a digital to analog conversion occurs and wherein the transfer rate provided to the subscriber is set. The line terminal equipment of such a system is not accessible to the subscriber. Consequently, if a subscriber wishes to make changes on or to the devices available to him, for example, to connect an additional device, the change must be performed by specialists who are able and qualified to carry out the necessary switching work in the line terminal equipment. This is time consuming and expensive.
Consequently, it is highly desirable to provide a line-conducted digital data telecommunication system that is not subject to such limitations.